Fix typo/bug introduced by 0679e056 (#3231, #3209, #1829, #946, #413)

diff --git a/imgui_widgets.cpp b/imgui_widgets.cpp
index 71153c2..e509c03 100644
--- a/imgui_widgets.cpp
+++ b/imgui_widgets.cpp
@@ -2970,7 +2970,7 @@
             DataTypeClamp(data_type, p_data, p_clamp_min, p_clamp_max);
 
         // Only mark as edited if new value is different
-        value_changed = memcmp(&data_type, p_data, data_type_size) != 0;
+        value_changed = memcmp(&data_backup, p_data, data_type_size) != 0;
         if (value_changed)
             MarkItemEdited(id);
     }